Image processing apparatus and image processing method

ABSTRACT

An image processing apparatus includes: image inputting portions for inputting a plurality of images; attribute inputting portions for inputting attribute information for the plurality of images; and an image combining processor for combining the plurality of images in accordance with an image combining ratio to generate a combined image. The image processing apparatus further includes: an attribute-information combining-ratio determining section for determining an attribute-information combining ratio for the plurality of images in accordance with the image combining ratio; an attribute-information combining processor for combining the attribute information for the plurality of images in accordance with the attribute-information combining ratio to generate combined attribute information; and an image processor for processing the combined image by switching image-processing in accordance with the combined attribute information.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from Japanese Patent Application No.2003-343566 filed Oct. 1, 2003, which is hereby incorporated byreference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates an image processing apparatus and an imageprocessing method for combining images.

2. Description of the Related Art

Conventionally, an image processing apparatus that combines a pluralityof images has been available to generate a single image. For combining aplurality of images, such an image processing apparatus discardsattribute information attached to the original images or selects theattribute information of one of the images.

However, when the attribute information is processed as described above,optimum attribute information is not supplied to a combined image. Thismakes it impossible to switch processing for optimum image processing inaccordance with attribute information.

SUMMARY OF THE INVENTION

The present invention has been made in view of the foregoing problem.The present invention makes it possible to perform optimum imageprocessing on a combined image in accordance with attribute information.

To achieve the foregoing, an aspect of the present invention provides animage processing apparatus. The image processing apparatus includes:image inputting portions for inputting a plurality of images; attributeinputting portions for inputting attribute information for the pluralityof images; and an image combining processor for combining the pluralityof images in accordance with the image combining ratio to generate acombined image. The image processing apparatus further includes: anattribute-information combining-ratio determining section fordetermining an attribute-information combining ratio for the pluralityof images in accordance with the image combining ratio; anattribute-information combining processor for combining the attributeinformation for the plurality of images in accordance with theattribute-information combining ratio to generate combined attributeinformation; and an image processor for processing the combined image byswitching image-processing in accordance with the combined attributeinformation.

The image processing apparatus may further include an imagecombining-ratio determining section for generating the image combiningratio for the plurality of images. Alternatively, the image processingapparatus may further comprise an image combining ratio input portionfor inputting the image combining ratio for the plurality of images.

The image combining ratio may be based on any of the plurality ofimages. Data of the any of the plurality of images may be digitizedusing a predetermined threshold to generate the image combined ratio.

The attribute-information combining-ratio determining section maydigitize the image combining-ratio by using a predetermined threshold todetermine the attribute-information combining ratio.

Another aspect of the present invention provides an image processingmethod. The image processing method includes: inputting a plurality ofimages; obtaining an image combining ratio for the plurality of images;and combining the plurality of images in accordance with the imagecombining ratio to generate a combined image. The image processingmethod further includes: determining an attribute-information combiningratio for the plurality of images in accordance with the image combiningratio; combining the attribute information for the plurality of imagesin accordance with the attribute-information combining ratio to generatecombined attribute information; and processing the combined image byswitching image-processing in accordance with the combined attributeinformation.

Another aspect of the present invention provides a program for executingthe image processing method described above.

Another aspect of the present invention provides a computer-readablestorage medium in which the program described above is stored.

Further features and advantages of the present invention will becomeapparent from the following description of the preferred embodimentswith reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the configuration of an image processingapparatus according to a first embodiment of the present invention.

FIGS. 2A to 2D are views for showing image-combining processing inaccordance with the first embodiment.

FIG. 3 is a view for showing an attribute-information combining ratio inaccordance with the first embodiment.

FIGS. 4A to 4C are views for showing attribute-information combiningprocessing in accordance with the first embodiment.

FIG. 5 is a block diagram of the configuration of an image processingapparatus according to a second embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Exemplary embodiments for carrying out the present invention aredescribed below in detail with reference to the attached drawings.

First Embodiment

FIG. 1 is a block diagram showing the configuration of an imageprocessing apparatus according to a first embodiment of the presentinvention.

Referring to FIG. 1, an image signal IMG1 is input to an input portion101. An image signal IMG2 is input to an input portion 102. Animage-combining ratio data BR is input to an input portion 103.Attribute-information data Z1 for the image signal IMG1 is input to aninput portion 104. Attribute-information data Z2 for the image signalIMG2 is input to an input portion 105. Using the image-combining ratiodata BR, an image combining processor 106 performs image-combiningprocessing on the image signals IMG1 and IMG2 to generate combined imagedata IMG3. In accordance with the image-combining ratio data BR, anattribute-information combining-ratio determining section 107 determinesattribute-information combining-ratio data ZBR to be applied to theattribute-information data Z1 and Z2. In accordance with thecombining-ratio data ZBR for the attribute-information data Z1 and Z2,an attribute-information combining processor 108 performs processing forcombining the attribute-information data Z1 and Z2 to generate combinedattribute-information data Z3. In accordance with the combinedattribute-information data Z3, an image processor 109 switchesparameters for processing to be performed on the combined image dataIMG3 and performs image processing suitable for the image attribute. Inthe first embodiment, the image processor 109 serves as a screenprocessor, as an example of an image processor. Processing performed bythe image processor 109 is not limited to screen processing, and thusmay be any processing for optimizing processing using combinedattribute-information data.

FIGS. 2A to 2D are views for illustrating image-combining processingaccording to the first embodiment. An image shown in FIG. 2A is based onthe image signal IMG1 and is a text (character) image in this case. Animage shown in FIG. 2B is based on the image signal IMG2 and includesthe sun and pyramids. In exemplary embodiments, each of the imagesignals IMG1 and IMG2 is an 8-bit signal and has 256 gradations from 0to 255 levels per pixel. FIG. 2C shows a conceptual image for theimage-combining ratio data BR. In exemplary embodiments, theimage-combining ratio data BR is also an 8-bit signal that is capable ofindicating the combining ratio in 0 to 255 levels per pixel. In theexample shown in FIG. 2C, however, for ease of illustration, the imageis expressed with two ratios, namely, black for BR=0 and white forBR=255. An image shown in FIG. 2D is an image provided by the combinedimage data IMG3 combined in accordance with the image-combining ratiodata BR.

The operation of the image processing apparatus in the first embodimentis described next.

As described above, the image signal IMG1 is input to the input portion101 and the image signal IMG2 is input to the input portion 102. Theimage-combining ratio data BR is input to the input portion 103. Inaccordance with the image-combining ratio data BR, the image combiningprocessor 106 performs image-combining processing on the image signalsIMG1 and IMG2 to generate the combined-image data IMG3 through the useof Equation (1) below:IMG 3(ij)=(IMG 1(ij)*(255−BR(ij))+IMG 2(ij)* BR(ij))/255  (1)

-   -   where (ij) indicates the position of each pixel, with i        indicating a horizontal pixel position and j indicating a        vertical pixel position. As can be understood from Equation (1),        when BR(ij) is 0, image signal values of IMG1(ij) are used as an        image signal for the pixel position (ij) of the combined image        data IMG3, and when BR(ij) is 255, signal values of IMG2(ij) are        used as an image signal for the pixel position (ij) of the        combined image data IMG3. Also, when BR(ij) is 128, half of the        signal values of the image signal IMG1 and half of the signal        values of the image signal IMG2 are added together and the        resulting values are used as an image signal.

In the example shown in FIG. 2C, for the image-combining ratio data BR,portions corresponding to the sun and the pyramids in the image that isshown in FIG. 2B and that is provided by the image signal IMG2 have avalue of 255 (i.e., white) and other portions have a value of 0 (i.e.,black). Thus, from Equation (1), signal values of IMG2(ij) are used forthe portions where BR(ij) is 255 and signal values of IMG1(ij) are usedfor the other portions to provide combined image data, thereby providingthe combined image shown in FIG. 2D.

The combined-image data IMG3 obtained as described above is sent to theimage processor 109.

On the other hand, the image-combining ratio data BR is also input tothe attribute-information combining-ratio determining section 107 inwhich the attribute-information combining-ratio data ZBR is determined.FIG. 3 shows an image for the attribute-information combining-ratio dataZBR, which is determined in accordance with the image-combining ratiodata BR for the image shown in FIG. 2C. The attribute-informationcombining-ratio data ZBR is determined based on Condition (2) below.If BR(ij)>TH0, ZBR(ij)=255If BR(ij)≦TH0, ZBR(ij)=0  (2)

-   -   where TH0 indicates a threshold. Thus, the image-combining ratio        data BR is digitized into binary data of 255 or 0. Since the        image-combining ratio data BR shown in FIG. 2C in the first        embodiment is binary data of 255 or 0, when TH0 is a value        between 0 and 254, the attribute-information combining-ratio        data ZBR is the same as the image-combining ratio data BR. While        the attribute-information combining-ratio data ZBR in this case        is expressed by 0 and 255 as the binary data, it can also be        expressed by 1-bit data with 0 and 1.

In accordance with the attribute-information combining-ratio data ZBR,the attribute-information combining processor 108 combines theattribute-information data Z1 for the image signal IMG1 with theattribute-information data Z2 for the image signal IMG2 to generate thecombined attribute-information data Z3.

As described above, through the digitization, the attribute-informationcombining-ratio data ZBR is converted into binary data that indicateseither 255 or 0. The attribute-information data Z2 is used for 255(i.e., white portions in FIG. 3) and the attribute-information data Z1is used for 0 (i.e., black portions in FIG. 3) to generate the combinedattribute-information data Z3.

FIGS. 4A to 4C are views for illustrating processing performed by theattribute-information combining processor 108. An image shown in FIG. 4Ais a conceptual image for the attribute-information data Z1 for theimage signal IMG1. An image shown in FIG. 4B is a conceptual image forthe attribute-information data Z2 for the image signal IMG2. An imageshown in FIG. 4C is a conceptual image for the combinedattribute-information data Z3.

In FIGS. 4A to 4C, the white portions have a “text” attribute, thehalftone portions have an “image” attribute, and each black portionrepresents a ground where nothing is rendered. The attribute data is2-bit data in which “0” indicates a ground (i.e., a black portion), “1”indicates an image attribute (i.e., a halftone portion), “2” indicates atext attribute (i.e., a white portion), and “3” is undefined.

As shown in FIG. 4A, with the attribute-information data Z1, a portionwhere a character is rendered has a text attribute (“2”, white) and theother portions indicate a ground (“0”, black). As shown in FIG. 4B, withthe attribute-information data Z2, portions where the sun and thepyramids are rendered have an “image” attribute (“1”, halftone) and theother portion indicates a ground (“0”, black). As shown in FIG. 4C, withthe attribute-information data Z3, the attribute-information signalvalues of the attribute-information data Z1 are used for the blackportion in FIG. 3 and the attribute-information signal values of theattribute-information data Z2 are used for the white portions in FIG. 3.

Comparison between the combined attribute-information data Z3 combinedas described and illustrated in FIG. 4C and the combined-image data IMG3illustrated in FIG. 2D shows that portions where characters are renderedhave the character attribute, portions where images are rendered havethe image attribute, and the other portions indicate a ground.

The combined attribute-information data Z3 generated by theattribute-information combining processor 108 is sent to the imageprocessor 109.

The image processor 109 performs screen processing, as described above.The image processor 109 has two screens, namely, a screen for acharacter and a screen for an image and is configured to switch betweenthe two screens in accordance with the combined attribute-informationdata Z3. The image processor 109 digitizes the combined-image data IMG3by using either of the screens that is suitable for the attribute ofeach pixel. For example, for pixels having an image attribute for whichhalftone stability is important in a printer using anelectrophotographic process or the like, it is desirable to digitizeimage data using a coarse screen pattern so that signals areconcentrated at highlighted portions. On the other hand, for pixelshaving a character attribute, it is desirable to improve the readabilityof low-contrast text using a fine screen pattern, while compromising thehalftone stability.

As described above, in the first embodiment, respective attributeinformation of images are combined to generate combined attributeinformation that is suitable for a combined image. This arrangement,therefore, makes it possible to switch processing for combining theimages in accordance with the attribute. That is, in accordance with theattribute of each pixel, processing is selectively switched such thatprocessing for a character is performed on a pixel having a textattribute and processing for an image is performed on a pixel having animage attribute, thereby improving the image quality.

Second Embodiment

FIG. 5 is a block diagram showing the configuration of an imageprocessing apparatus according to a second embodiment of the presentinvention.

In the second embodiment, the input portion 103 (shown in FIG. 1) forthe combining-ratio data BR is replaced with an image combining-ratiodetermining section 501. Since the other sections have the sameconfigurations as those shown in FIG. 1 and described above, they aredenoted with the same reference numerals and the descriptions thereofare not described in further detail here. The image combining-ratiodetermining section 501 receives an image signal IMG2 from input portion102 and uses Condition (3) below to determine image-combining ratio dataBR.If IMG 2(ij)>TH1, BR(ij)=255If IMG 2(ij)≦TH1, BR(ij)=0  (3)where TH1 indicates a threshold.

When the image signal IMG2 has data for an image as shown in FIG. 2B,for example, digitizing the image signal IMG2 for TH1=50 yields an imagefor the image-combining ratio data BR as shown in FIG. 2C.

Since the other processing is analogous to that in the first embodiment,the description thereof is omitted here.

Thus, the second embodiment can provide the same advantages as the firstembodiment.

Even though the descriptions of the first and second embodiments havebeen given in a case in which two images are combined, the presentinvention is readily applicable to a case in which three or more imagesare combined. In such a case, two or more parameters are appropriatelyused for the image combining-ratio data, and it is preferable that datafor selecting the attribute information of an image having the highestimage combining ratio is generated as the attribute-informationcombining-ratio data ZBR.

Other Embodiments

The above-described embodiments of the present invention can be achievedby supplying a storage medium (or recording medium) storingsoftware-program code for realizing the features of the illustratedembodiments to a system or apparatus so that a computer (or centralprocessing unit (CPU) or micro-processing unit (MPU)) of the system orapparatus reads and executes the program code. In such a case, theprogram code that is read from the storage medium achieves the featuresof the embodiments and the storage medium in which the program code isstored is also encompassed by the present invention. Further, not onlyis the program code that is read from the computer executed to achievethe features of the illustrated embodiments, but also an operatingsystem (OS) or the like that is running on the computer may perform partor all of the actual processing in accordance with an instruction of theprogram code to achieve the features of the illustrated embodiment.Examples of the storage medium for storing the program code include aflexible disk, hard disk, read-only memory (ROM), random-access memory(RAM), magnetic tape, nonvolatile memory card, compact disk—ROM(CD-ROM), compact disk—recordable (CD-R), digital versatile disk (DVD),optical disk, magneto-optical disk, and magneto-optical (MO). Computernetworks, such as a local area network (LAN) and a wide area network(WAN) can be used to supply the program code.

Additionally, after the program code that is read from the storagemedium is stored in a memory that is provided in a plug-in card insertedinto the computer or an expansion section connected to the computer, aCPU or the like that is provided in the plug-in card or the expansionsection may perform part or all of the actual processing in accordancewith instructions of the program code to achieve the features of theillustrated embodiments.

The present invention makes it possible to output an image as intendedby a user who desires to output a combined image corresponding to thecolor mode of an input image. In addition, the present invention makesit possible to output a combined image that is faithful to an outputcolor mode desired by the user through the use of combined color modepriority setting.

While the present invention has been described with reference to whatare presently considered to be the preferred embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments. On the contrary, the invention is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims. The scope of the following claims is to beaccorded the broadest interpretation so as to encompass all suchmodifications and equivalent structures and functions.

1. An image processing apparatus comprising: image inputting means forinputting a plurality of images; attribute inputting means for inputtingattribute information for the plurality of images; image combining meansfor combining the plurality of images in accordance with an imagecombining ratio for the plurality of images to generate a combinedimage; attribute-information combining-ratio determining means fordetermining an attribute-information combining ratio for the pluralityof images in accordance with the image combining ratio;attribute-information combining means for combining the attributeinformation for the plurality of images in accordance with theattribute-information combining ratio to generate combined attributeinformation; and image processing means for processing the combinedimage by switching image-processing in accordance with the combinedattribute information.
 2. The image processing apparatus according toclaim 1, further comprising image combining ratio generating means forgenerating the image combining ratio for the plurality of images.
 3. Theimage processing apparatus according to claim 1, further comprisingimage combining ratio input means for inputting the image combiningratio for the plurality of images.
 4. The image processing apparatusaccording to claim 1, wherein the image combining ratio is based on anyof the plurality of images.
 5. The image processing apparatus accordingto claim 4, wherein data of the any of the plurality of images isdigitized using a predetermined threshold to generate the imagecombining ratio.
 6. The image processing apparatus according to claim 1,wherein the attribute-information combining-ratio determining meansdigitizes the image combining ratio by using a predetermined thresholdto determine the attribute-information combining ratio.
 7. An imageprocessing apparatus comprising: image inputting portions configured toinput a plurality of images; attribute inputting portions configured toinput attribute information for the plurality of images; an imagecombining processor configured to combine the plurality of images inaccordance with an image combining ratio to generate a combined image;an attribute-information combining-ratio determining section configuredto determine an attribute-information combining ratio for the pluralityof images in accordance with the image combining ratio; anattribute-information combining processor configured to combine theattribute information for the plurality of images in accordance with theattribute-information combining ratio to generate combined attributeinformation; and an image processor configured to process the combinedimage by switching image-processing in accordance with the combinedattribute information.
 8. The image processing apparatus according toclaim 7, further comprising an image combining-ratio determining sectionconfigured to generate the image combining ratio for the plurality ofimages.
 9. The image processing apparatus according to claim 7, furthercomprising an image combining ratio input portion configured to inputthe image combining ratio for the plurality of images.
 10. The imageprocessing apparatus according to claim 7, wherein the image combiningratio is based on any of the plurality of images.
 11. The imageprocessing apparatus according to claim 10, wherein data of the any ofthe plurality of images is digitized using a predetermined threshold togenerate the image combined ratio.
 12. The image processing apparatusaccording to claim 7, wherein the attribute-information combining-ratiodetermining section is configured to digitize the image combining-ratioby using a predetermined threshold to determine theattribute-information combining ratio.
 13. An image processing methodcomprising: inputting a plurality of images; obtaining an imagecombining ratio for the plurality of images; combining the plurality ofimages in accordance with the image combining ratio to generate acombined image; determining an attribute-information combining ratio forthe plurality of images in accordance with the image combining ratio;combining the attribute information for the plurality of images inaccordance with the attribute-information combining ratio to generatecombined attribute information; and processing the combined image byswitching image-processing in accordance with the combined attributeinformation.
 14. The image processing method according to claim 13,wherein the image combining ratio is based on any of the plurality ofimages.
 15. The image processing apparatus according to claim 14,wherein the image combining ratio is generated by digitizing data of theany of the plurality of images using a predetermined threshold.
 16. Theimage processing apparatus according to claim 13, wherein determiningthe attribute-information combining ratio for the plurality of imagescomprises determining the attribute-information combining ratio for theplurality of images by digitizing the image combining ratio using apredetermined threshold.
 17. A program for executing the imageprocessing method according to claim
 13. 18. A computer-readable storagemedium in which the program according to claim 17 is stored.